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180+ Pharmaceutical Organic Chemistry 3 Solved MCQs
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Bachelor of Pharmacy (B. Pharma) , Pharmacy .
| 1. |
1 Hexane and 3-methylpentane are examples of: |
| A. | Enantiomers. |
| B. | Stereoisomer. |
| C. | Diastereomers. |
| D. | Constitutional isomers. |
| Answer» D. Constitutional isomers. | |
| 2. |
Cis-trans isomers are: |
| A. | Diastereomers. |
| B. | Enantiomers. |
| C. | Geometric isomers. |
| D. | Constitutional isomers. |
| Answer» C. Geometric isomers. | |
| 3. |
(2R,4S) –2,4–Dichloropentane and (2S,4R)-2,4-dichloropentane are: |
| A. | Enantiomers |
| B. | Diastereomers |
| C. | identical |
| D. | conformational isomers |
| Answer» C. identical | |
| 4. |
Which of the following molecules is achiral? |
| A. | (2R,3R)-2,3-Dichloropentane |
| B. | (2R,3S)-2,3-Dichloropentane |
| C. | (2S,4S)-2,4-Dichloropentane |
| D. | (2S,4R)-2,4-Dichloropentane |
| Answer» D. (2S,4R)-2,4-Dichloropentane | |
| 5. |
Which statement is not true for a meso compound? |
| A. | The specific rotation is 0º. |
| B. | There are one or more planes of symmetry. |
| C. | More than one stereogenic center must be present. |
| D. | The stereo chemical labels, (R) and (S), must be identical for each stereogenic centre. |
| Answer» D. The stereo chemical labels, (R) and (S), must be identical for each stereogenic centre. | |
| 6. |
Which is a meso compound? |
| A. | (2R,3R)-2,3-Dibromobutane |
| B. | (2R,3S)-2,3-Dibromopentane |
| C. | (2R,4R)-2,4-Dibromopentane |
| D. | (2R,4S)-2,4-Dibromopentane |
| Answer» D. (2R,4S)-2,4-Dibromopentane | |
| 7. |
What is the percent composition of a mixture of (S)-(+)-2-butanol,[!] D/25 = +13.52º, and (R)-(-)-2-butanol,[!] D/25 = -13.52º, with a specific rotation [!] D/25 = +6.76º? |
| A. | 75%(R) 25%(S) |
| B. | 25%(R) 75%(S) |
| C. | 50%(R) 50%(S) |
| D. | 67%(R) 33%(S) |
| Answer» B. 25%(R) 75%(S) | |
| 8. |
Which one of the following can exist in optically active forms? |
| A. | cis-1,3-Dichlorocyclohexane |
| B. | trans-1,3-Dichlorocyclohexane |
| C. | cis-1,4-Dichlorocyclohexane |
| D. | tr |
| Answer» D. tr | |
| 9. |
Which of these is a comparatively insignificant factor affecting the magnitude of Specific optical rotation? |
| A. | Concentration of the substance of interest |
| B. | Purity of the sample |
| C. | Temperature of the measurement |
| D. | Length of the sample tube |
| Answer» C. Temperature of the measurement | |
| 10. |
What can be said with certainty if a compound has [!] D/25 = -9.25º ? |
| A. | The compound has the (S) configuration. |
| B. | The compound has the (R) configuration. |
| C. | The compound is not a meso form. |
| D. | The compound possesses only one stereogenic center. |
| Answer» C. The compound is not a meso form. | |
| 11. |
An alkane which can exhibit optical activity is: |
| A. | Neopentane |
| B. | Isopentane |
| C. | 3–Methylpentane |
| D. | 3–Methylhexane |
| Answer» D. 3–Methylhexane | |
| 12. |
In the absence of specific data, it can only be said that (R)–2–bromopentane is: |
| A. | Dextrorotatory (+). |
| B. | Levorotatory (–). |
| C. | Optically inactive. |
| D. | Chiral. |
| Answer» D. Chiral. | |
| 13. |
If a solution of a compound (30.0 g/100 mL of solution) has a measured rotation of +15º in a 2 dm tube, the specific rotation is: |
| A. | +50º |
| B. | +25º |
| C. | +15º |
| D. | +7.5º |
| Answer» B. +25º | |
| 14. |
Which compound would show optical activity? |
| A. | cis 1,4- Dimethylcyclohexane |
| B. | trans 1,4- Dimethylcyclohexane |
| C. | cis 1,4- Dimethylcycloheptane |
| D. | tr |
| Answer» D. tr | |
| 15. |
Of the compounds which correspond to the general name "dichlorocyclobutane", how many are optically active? |
| A. | 0 |
| B. | 1 |
| C. | 2 |
| D. | 3 |
| Answer» C. 2 | |
| 16. |
Which of the following is true of any (S)-enantiomer? |
| A. | It rotates plane-polarized light to the right. |
| B. | It rotates plane-polarized light to the left. |
| C. | It is a racemic form. |
| D. | It is the mirror image of the corresponding (R)-enantiomer. |
| Answer» D. It is the mirror image of the corresponding (R)-enantiomer. | |
| 17. |
Enantiomers are: |
| A. | Molecules that have a mirror image. |
| B. | Molecules that have at least one stereogenic center. |
| C. | Non-superposable molecules. |
| D. | Non-superposable molecules that are mirror images of each other. |
| Answer» D. Non-superposable molecules that are mirror images of each other. | |
| 18. |
Which of the following is NOT true of enantiomers? They have the same: |
| A. | Boiling point. |
| B. | Melting point. |
| C. | Specific rotation. |
| D. | Density. |
| Answer» C. Specific rotation. | |
| 19. |
Which statement is true of 1,3-dimethylcyclobutane?. |
| A. | Only one form of the compound is possible. |
| B. | Two diastereomeric forms are possible. |
| C. | Two sets of Enantiomers are possible. |
| D. | Two enantiomeric forms and one meso comp. |
| Answer» B. Two diastereomeric forms are possible. | |
| 20. |
CH3CHBrCH2CHClCH3 is the generalized representation of what number of stereo isomers? |
| A. | 3 |
| B. | 4 |
| C. | 5 |
| D. | 6 |
| Answer» B. 4 | |
| 21. |
For the generalized structure BrCH2CHClCH2CHClCH2Br there exists what number of stereoisomers? |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 6 |
| Answer» C. 4 | |
| 22. |
How many discrete dimethylcyclopropanes are there? |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 5 |
| Answer» C. 4 | |
| 23. |
What is the molecular formula for the alkenes of smallest molecular weight which possesses a stereogenic center? |
| A. | C4H10 |
| B. | C5H12 |
| C. | C6H14 |
| D. | C7H16 |
| Answer» D. C7H16 | |
| 24. |
How many chiral stereoisomers can be drawn for CH3CHFCHFCH (CH3)2? |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» D. 4 | |
| 25. |
How many different compounds are there which correspond to the general name "3-(1- methylbutyl) cyclobutanol”? |
| A. | 2 |
| B. | 4 |
| C. | 6 |
| D. | 8 |
| Answer» B. 4 | |
| 26. |
Which of the statements below correctly describes an achiral molecule? |
| A. | The molecule has a nonsuperimposable mirror image. |
| B. | The molecule exhibits optical activity when it interacts with plane-polarized light. |
| C. | The molecule has an enantiomer. |
| D. | The molecule might be a meso form. |
| Answer» D. The molecule might be a meso form. | |
| 27. |
Which of the following statements correctly pertains to a pair of enantiomers? |
| A. | They rotate the plane of polarized light by exactly the same amount and in opposite directions. |
| B. | They rotate the plane of polarized light by differing amounts and in opposite directions. |
| C. | They rotate the plane of polarized light by differing amounts and in the same direction. |
| D. | They have different melting points. |
| Answer» A. They rotate the plane of polarized light by exactly the same amount and in opposite directions. | |
| 28. |
A mixture of equal amounts of two enantiomers __________. |
| A. | is called a racemic mixture |
| B. | is optically inactive |
| C. | implies that the enantiomers are meso forms |
| D. | both A and B |
| Answer» D. both A and B | |
| 29. |
__________ is the use of an optically active reagent or catalyst to convert an optically inactive starting material into an optically active product. |
| A. | Asymmetric induction |
| B. | Racemization |
| C. | Optical reduction |
| D. | Meso effection |
| Answer» A. Asymmetric induction | |
| 30. |
Which of the following statements is (are) true for the compound (R)-2-butanol? |
| A. | This compound is chiral. |
| B. | This compound is optically active. |
| C. | This compound has an enantiomer. |
| D. | all of the above |
| Answer» D. all of the above | |
| 31. |
Which of the following statements is (are) true for the compound (3R, 4R)-3,4-dimethylhexane? |
| A. | This compound is chiral. |
| B. | The enantiomer of this compound is (3S, 4S)-3,4-dimethylhexane. |
| C. | This compound is a diastereomer of (3R, 4S)-3,4-dimethylhexane. |
| D. | all of the above |
| Answer» D. all of the above | |
| 32. |
Which of the following statements is (are) true for the compound cis-1,2-dichlorocyclopropane? |
| A. | This compound is chiral. |
| B. | The enantiomer of this compound is trans-1,2-dichlorocyclopropane. |
| C. | This compound contains no asymmetric carbons. |
| D. | none of the above |
| Answer» D. none of the above | |
| 33. |
How many asymmetric carbon atoms are present in the following compound?
|
| A. | 0 |
| B. | 1 |
| C. | 2 |
| D. | 3 |
| Answer» B. 1 | |
| 34. |
How many chiral carbon atoms are present in the following compound?
|
| A. | 0 |
| B. | 1 |
| C. | 2 |
| D. | 3 |
| Answer» A. 0 | |
| 35. |
Which of the following terms correctly describe(s) the structural relationship between cis-1,3- dimethylcyclopentane and trans-1,3-dimethylcyclopentane? |
| A. | enantiomers |
| B. | diastereomers |
| C. | geometric isomers |
| D. | both B and C |
| Answer» D. both B and C | |
| 36. |
How many diastereomers are there of the molecule shown below?
|
| A. | 0 |
| B. | 2 |
| C. | 4 |
| D. | 6 |
| Answer» D. 6 | |
| 37. |
How many enantiomers are there of the molecule shown below?
|
| A. | 0 |
| B. | 2 |
| C. | 4 |
| D. | 6 |
| Answer» A. 0 | |
| 38. |
What term describes the structural relationship between (E)- and (Z)-2-pentene? |
| A. | Constitutional isomers |
| B. | Enantiomers |
| C. | Geometric isomers |
| D. | Conformers |
| Answer» C. Geometric isomers | |
| 39. |
Compounds which have different arrangements of atoms in space while having same atoms bonded to each other are said to have |
| A. | position isomerism |
| B. | functional group isomerism |
| C. | chain isomerism |
| D. | stereoisomerism |
| Answer» D. stereoisomerism | |
| 40. |
Which of the following can make difference in optical isomers? |
| A. | heat |
| B. | temperature |
| C. | polarized light |
| D. | pressure |
| Answer» C. polarized light | |
| 41. |
Which of the following terms best describes the following pair of molecules?
|
| A. | Isomers |
| B. | Constitutional isomers |
| C. | Configurational isomers |
| D. | Geometrical isomers |
| Answer» D. Geometrical isomers | |
| 42. |
What is the relationship between the two groups in the following molecules?
|
| A. | They are equatorial to one another |
| B. | They are axial to one another |
| C. | They are cis to one another |
| D. | They are trans to one another |
| Answer» A. They are equatorial to one another | |
| 43. |
What is the stereochemical relationship between the following two molecules?
|
| A. | Geometrical isomers |
| B. | Enantiomers |
| C. | Diastereomers |
| D. | Identical |
| Answer» D. Identical | |
| 44. |
Which of the following is an alkane which can exhibit optical activity? |
| A. | Neopentane |
| B. | Isopentane |
| C. | 3–Methylpentane |
| D. | 3–Methylhexane |
| Answer» D. 3–Methylhexane | |
| 45. |
Hexane and 3-methylpentane are examples of: |
| A. | enantiomers. |
| B. | stereoisomers. |
| C. | diastereomers. |
| D. | constitutional isomers. |
| Answer» D. constitutional isomers. | |
| 46. |
Which of these is a comparatively insignificant factor affecting the magnitude of specific optical rotation. |
| A. | Concentration of substance of interest |
| B. | Temperature of measurement |
| C. | Length of the sample tube |
| D. | All of the above |
| Answer» D. All of the above | |
| 47. |
How many chiral stereoisomers can be drawn for CH3CHFCHFCH(CH3)2? |
| A. | 2 |
| B. | 4 |
| C. | 6 |
| D. | 8 |
| Answer» B. 4 | |
| 48. |
How many different compounds are there which correspond to the general name "3-(1- methylbutyl)cyclobutanol”? |
| A. | 2 |
| B. | 4 |
| C. | 6 |
| D. | 8 |
| Answer» B. 4 | |
| 49. |
Which of the following is NOT true of enantiomers? They have the same: |
| A. | boiling point. |
| B. | melting point. |
| C. | specific rotation. |
| D. | chemical reactivity toward achiral reagents. |
| Answer» D. chemical reactivity toward achiral reagents. | |
| 50. |
Which statement is true for 1,3-dimethylcyclobutane? |
| A. | Only one form of the compound is possible |
| B. | Two diastereomeric forms are possible. |
| C. | Two enantiomeric forms and one meso compound are possible. |
| D. | None of the above. |
| Answer» B. Two diastereomeric forms are possible. | |
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